The polyamines spermidine and spermine and their precursor putrescine are small aliphatic cations under normal physiological conditions and are intimately associated with growth and differentiation of mammalian cells, yet their exact cellular functions have not been solved (Jänne, J., Alhonen, L., and Leinonen, P. (1991) Ann. Med. 23, 241–259). In attempts to elucidate the physiological roles of the polyamines, a number of transgenic mouse and rat lines with genetically altered polyamine metabolism have been generated. The activation of polyamine biosynthesis through an overexpression of ornithine decarboxylase (ODC) brings about many interesting phenotypic changes, such as male infertility (Halmekytö, M., Hyttinen, J.-M., Sinervirta, R., Utriainen, M., Myöhänen, S., Voipio, H.-M., Wahlfors, J., Sydjänen, S., Syjänen, K., Alhonen, L., and Jänne, J. (1991) J. Biol. Chem. 266, 19746–19751; Hakovirta, H., Keiski, A., Toppari, J., Halmekytö, M., Alhonen, L., Jänne, J., and Parvinen, M. (1993) Mol. Endocrinol. 7, 1430–1436), yet these studies are complicated by the fact that overexpression of ODC only increases tissue putrescine pools, as the latter diamine is not further converted to spermidine and spermine (Halmekytö, M., Alhonen, L., Alakuijala, L., and Jänne, J. (1993) Biochem. J. 291, 505–508; Suppola, S., Heikkinen, S., Parkkinen, J. J., Uusi-Oukari, M., Korhonen, V. P., Keinänen, T., Alhonen, L., and Jänne, J. (2001) Biochem J. 358, 343–348).
Much more severe distortion of tissue polyamine pools has been achieved by activation of polyamine catabolism through an overexpression of spermidine/spermine N1-acetyltransferase (SSAT) in transgenic rodents. The latter enzyme catalyzes the rate-controlling reaction in the catabolism of spermidine and spermine. After being acetylated, N1-acetylspermidine is converted to putrescine and N1-acetylspermine to spermidine by the action of polyamine oxidase (PAO) (Casero, R. A., and Pegg, A. E. (1993) FASEB J. 7, 653–661). Overexpression of SSAT in transgenic rodents results in profound changes in tissue polyamine pools, such as massive accumulation of putrescine, appearance of N1-acetylspermidine and decreases in spermidine and/or spermine pools (Pietilä, M., Alhonen, L., Halmnekytö, M., Kanter, P., Jänne, J., and Porter, C. W. (1997) J. Biol. Chem. 272, 18746–18751). The alterations in polyamine homeostasis are accompanied by bizarre phenotypic changes, such as early and permanent loss of hair, extensive wrinkling of the skin upon aging, lack of subcutaneous fat (Pietilä, M., Alhonen, L., Halmekytö, M., Kanter, P., Jänne, J., and Porter, C. W. (1997) J. Biol. Chem. 272, 18746–18751) and reduced life span (Suppola, S., Heikkinen, S., Parkkinen, J. J., Uusi-Oukari, M., Korhonen, V. P., Keinänen, T., Alhonen, L., and Jänne, J. (2001) Biochem J. 358, 343–348). Transgenic rats have been generated in which SSAT expression is driven by the heavy metal-inducible mouse metallothionein I promoter (Alhonen, L., Parkkinen, J. J., Keinänen, T., Sinervirta, R. Herzig, K.-H., and Jänne, J. Proc. Natl. Acad. Sci. U.S.A., 97, 8290–8295 (2000)). The metallothionein promoter directs the expression of SSAT mainly into liver and pancreas in a heavy metal-inducible fashion. Exposure of the transgenic rats to nontoxic doses of zinc resulted in an immense induction of SSAT activity in the pancreas, a profound depletion of pancreatic spermidine and spermine pools and acute pancreatitis (Alhonen, L., Parkkinen, J. J., Keinänen, T., Sinervirta, R., Herzig, K. H., and Jänne, J. (2000) Proc. Natl. Acad. Sci. U.S.A. 97, 8290–8295). The fact that pancreatitis could not be prevented by inhibition of PAO, which generates hydrogen peroxide and a reactive aldehydes, suggested that the organ inflammation was causally related to the profound depletion of spermidine and spermine (Alhonen, L., Parkkinen, J. J., Keinänen, T., Sinervirta, R., Herzig, K. H., and Jänne, J. (2000) Proc. Natl. Acad. Sci. U.S.A. 97, 8290–8295).
Acute pancreatitis is a common clinical problem which remains evasive of specific therapy (Leach S D, Gorelick S, Modlin I M: New perspectives on acute pancreatitis. Scan J Gastroenterol 27 Suppl 192:29–38, 1992). Each year more than 210,000 admissions to U.S. hospitals are caused by acute pancreatitis while another 150,000 are due to chronic pancreatitis. Pancreatitis is most often caused by alcoholism or biliary tract disease. Less commonly, it is associated with hyperlipemia, hyperparathyroidism, abdominal trauma, vasculitis or uremia. The average length of hospitalization for the acute disease is 12.4 days, with a significant number of patients staying much longer because of associated complications.
The overall mortality for acute pancreatitis varies between 6 and 18% and can raise as high as 50% in the more fulminant form (Steinberg W, Tenner S: Acute pancreatitis. N Eng J Med 330:1198–1220, 1994; Imrie C W, Whyte A S: A prospective study of acute pancreatitis. Br J Surg 62:490–494, 1975; Jacobs M L, Daggett W M, et al: Acute pancreatitis: Analysis of factors influencing survival. Ann Surg 185:43–51, 1977). Interestingly, the prognosis for this disease appears more dependent upon its systemic manifestations and complications than upon the severity of the local pancreatic inflammation (Imrie and Whyte, 1975; Jacobs et al., 1977). In fact, as many as 60% of deaths from acute pancreatitis which occur within one week of onset can be attributed to adult respiratory distress syndrome (ARDS), which cannot be distinguished from sepsis-associated ARDS (Steinberg and Tenner, 1994; Jacobs et al., 1977).
Chronic pancreatitis develops in those patients who continue to drink after their first bout of pancreatitis or those with gallstone pancreatitis for unknown reasons. The recurrent bouts of acute pancreatitis subsequently become less severe and less life threatening. The typical patient with chronic pancreatitis, however, is admitted to the hospital approximately one to two times per year for the rest of their lives. These patients have a decreased life span when compared to their peers (Imrie and Whyte, 1975; Steinberg and Tenner, 1994). Despite the less severe course of the disease, it causes chronic debilitating pain and numerous hospitalizations and loss of productivity. These patients often have chronic pain to such a degree that they become dependent upon narcotics or require operative intervention in attempts to remove or ablate some of the chronically inflamed pancreas.
Chronic ethanol abuse is one of the most common cause of acute and chronic pancreatitis in the West, yet the pathophysiology of this disease remains poorly understood (Steinberg and Tenner, 1994). There are few medical therapies or pharmacologic agents currently available which have been shown to decrease the severity, duration, complication rate, or mortality for this common disease. Care for these patients, regardless of the etiology, remains primarily supportive, with attention directed towards maintaining an adequate circulating blood volume, supporting renal and respiratory systems, and providing adequate nutrition. This lack of specific therapy has prompted a great number of prospective trials during the past two decades in hopes of finding some way to decrease the progression and severity of this disease. To date, specific therapy remains unknown and a search for new, more effective modalities is necessary.
Current specific treatments in use and/or proposed for pancreatitis comprise, for example, using bradykinin-antagonists, using IL-11, IL-1 block such as Interleukin-1 converting enzyme (ICE) antagonist, and insulin sensitizers.
When transgenic rats in which SSAT expression is driven by the mouse metallothionein I promoter were subsequently subjected to partial hepatectomy, a striking stimulation of SSAT activity was observed that was associated with a rapid depletion of the hepatic spermidine pool at 24 h after operation (Alhonen, L., Räsänen, T. L., Sinervirta, R., Parkkinen, J. J., Korhonen, V. P., Pietilä, M., and Jänne, J. (2002) Biochem. J. 362, 149–153). Under these conditions, the transgenic rats failed to initiate liver regeneration, as judged by lack of proliferative activity and organ weight gain. The regeneration was restored only after spermidine concentration returned to the preoperative level, presumably due to enhanced ODC activity (Alhonen, L., Räsänen, T. L., Sinervirta, R., Parkkinen, J. J., Korhonen, V. P., Pietilä, M., and Jänne, J. (2002) Biochem. J. 362, 149–153).
Accordingly, the present invention is directed, among other important ends, to novel methods for the treatment and prevention of pancreatitis using polyamines and/or polyamine analogues, and to methods of stimulating liver regeneration using polyamines and/or polyamine analogues.